Gwen taking Christina's chair

TMZ says it has learned Gwen Stefani has signed on to be a judge on The Voice, subbing for the enceinte Christina Aguilera during Season 7, which starts taping in June.

Producers started looking for new blood in February after Aguilera announced she was pregnant.

NBC (which had no comment) reportedly wanted her to stay during her pregnancy, but she's having a difficult time already and ultimately bowed out. (She was just fine on Saturday, though, tweeting, "So blissful in taking this time for creating all things blossoming new on the horizon . . . album, baby & beautiful music to come."

TMZ says she has already signed on to rotate back into her spinning chair for Season 8.

Captain America: Unstoppable

Marvel's superhero in Captain America: The Winter Soldier claimed a third straight box office win, collecting $26.6 million at the domestic box office to beat the colorful birds of animated film Rio 2, which took in $22.5 million.

Heaven is for Real, based on a best-selling Christian book about a boy who claims to have witnessed heaven during emergency surgery, was a strong third at U.S. and Canadian theaters with $21.5 million. Starring Greg Kinnear, it opened Wednesday night and was expected to total $28.5 million in ticket sales through Sunday, according to Sony.

"This result is really terrific and far exceeded our expectations," said Rory Bruer, Sony president of worldwide distribution. He noted that the film appealed "not only to a faith-based audience but to a more mainstream one. It's a subject people like to talk about, and it has provoked dialog."

Transcendence, the science fiction thriller starring Johnny Depp as an artificial intelligence researcher, was a disappointing fourth with $11.2 million. It's the directorial debut of longtime cinematographer Wally Pfister, who won the 2010 Oscar for Inception. With a budget of $100 million, it was projected to open with ticket sales of $21 million.